Humans fleeing an ecologically and socially collapsing Earth have founded a colony on Celestis, a planet that keeps one face turned toward its primary. The native Aboriginals were, apparently, enslaved by a second race, older and more powerful, known as demons, which the humans quickly decimated. To avoid re-enslavement, the Aboriginals accepted surgical and pharmacological intervention to make themselves more humanlike. But now a liberation movement arises among the natives -- galvanized, incongruously, by what seems to be a demon. Young diplomat Simon Mayaram is ordered by his superior to attend celebrations at a remote country estate. During his visit, the estate is attacked by revolutionaries. Humans and altered Aboriginals are slaughtered; Simon is captured along with Katharine Styreme, the humanlike ""daughter"" of a wealthy Aboriginal, and conveyed to a prison on the dark side of the planet. Fortuitously, they manage to escape during an assault by anti-Aboriginal human terrorists. But without her drugs, Katharine begins to revert to her true nature, and she develops insights into the complex relationship between Aboriginals and demons -- a relationship willfully misunderstood by Simon and his fellow humans because of its disturbingly close resemblance to human homosexual contact. Thoughtful, unsettling, and provocative; a pity that Park (The Cult of Loving Kindness, 1991, etc.) didn't develop the underlying ecological assumptions with greater rigor and clarity.